In a manufacturing of a wafer-level chip scale packages (WLCSP), a metal pad is electrically coupled to a solder ball. A passivation layer and a protective layer are on the metal pad. The metal pad is connected to the solder ball through some openings in the passivation layer and the protective layer.
Some dies in WLCSP that are formed on a wafer is separated by a process referred to as a singulation. These wafers are aligned and singulated into some individual dies. Some alignment marks on a wafer are used for aligning a wafer before singulation. A clear and recognizable alignment mark can result in an accurate singulation process.